Apparatus for automatically handling palletized loads



M. FREY Jan. 14, 1969 APPARATUS FOR AUTOMATICALLY HANDLING PALLETIZED LOADS Filed Sept. 12, 1966 Sheet R mf E 5% w M W B M 4 4 w, 90 NOT LOAD'H I Jan. 14, 1969 M. FREY APPARATUS FOR AUTOMATICALLY HANDLING PALLETIZED LOADS Filed Sept. 12, 1966 INVEN'I'OR H 100% w M Z a. O

a m w m 5 2 A Max Frey [M QLZ/MM United States Patent 3,421,641 APPARATUS FOR AUTOMATICALLY HANDLING PALLETIZED LOADS Max Frey, Portland, Oreg., assignor to Cascade Corporation, Portland, Oreg., a corporation of Oregon Filed Sept. 12, 1966, Ser. No. 578,705 U.S. Cl. 214-38 11 Claims Int. Cl. B65g 67/00 ABSTRACT OF THE DISCLOSURE Apparatus for handling palletized loads including a support platform and a transfer device for transferring a load to and from the platform. Sensing elements are provided on the platform which indicate the load condition existing thereon. Mechanism included for controlling operation of the transfer device controls such operation in response to the load condition on the platform as indicated by the sensing elements.

This invention relates to apparatus for automatically handling a palletized load.

In a specific and preferred embodiment of the invention, the apparatus employs a pair of lift forks which may be extended beneath a properly palletized load in the space provided by the pallet, and operated to transfer the load from one location to another. The apparatus is described herein as mounted on the deck of a ship, closely adjacent a load station on the deck, although it should be understood that the apparatus has utility in other loadhandling organizations. In one mode of operation, the apparatus receives loads which are brought to the station from outside the ship, and transfers such loads to an elevator on the ship where they are conveyed to storage regions below the deck. In another mode of operation, the apparatus operates to transfer loads, which it has already once handled, from the elevator back to the load station.

The apparatus also includes a load support platform, and during the mode of operation where loads are received from the load station, such loads are placed from the station onto the support platform and the lift forks of the apparatus are operated to transfer the loads away from the platform. During the other mode of operation, the forks are operated to transfer loads to the platform, and such loads are then removed from the platform to the load station.

In order for such apparatus to perform satisfactorily, there are a number of factors which must be considered. To begin with, the apparatus, in its first-mentioned mode of operation, must be capable of distinguishing between a palletized and a nonpalletized load which is placed on the support platform from the load station, for the reason that the lift forks of the apparatus cannot be extended beneath a nonpalletized load where no space is provided for the forks. Secondly, during this mode of operation, the apparatus must be capable of determining that such a load is properly positioned on the platform whereby the lift forks, when operated to pick up and transfer the load away from the platform, will carry the load properly. Additionally, during the mode of operation where the forks of the apparatus are used to place loads on the platform, some provision should be made to assure that the platform is free of any load before a load is placed on it.

A general object of the invention, therefore, is to provide apparatus for handling palletized loads which will operate in a highly practical and satisfactory manner, taking into account the various factors indicated above.

More specifically, an object of the invention is to provide such apparatus which is capable of distinguishing between a palletized and a nonpalletized load, including means which prevents it from handling a nonpalletized load.

Another object is to provide apparatus of the type described which further includes means for determining whether a palletized load that is presented to the apparatus for handling is properly postioned relative to the apparatus. If the load is not properly positioned, such means prevents operation of the apparatus.

A further object is to provide such apparatus which includes means preventing it from accidentally stacking one load upon another.

These and other objects and advantages attained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a somewhat simplified plan view illustrating apparatus as contemplated herein for handling palletized loads, and how such apparatus may be employed;

FIG. 2 is a view taken generally along the line 2-2 in FIG. 1, illustrating how visual indicating means, as contemplated herein, would appear during a mode of operation for the apparatus referred to as an unloading mode of operation; and

FIG. 3 illustrates, diagrammatically, detecting means and control means which are employed in the apparatus of FIG. 1.

Turning now to the drawings, and with reference first to FIG. 1, shown generally at 10 is apparatus as contemplated herein for handling palletized loads including a load support platform 12 having front and rear ends 12a, 12b, respectively. A load transfer device 14 is poistioned closely adjacent the platform. In the embodiment illustrated, platform 12 and transfer device 14 may be suitably mounted on the deck of a cargo-carrying ship partial- 1y shown at 16.

Extending through an opening 18 provided in deck 16, closely adjacent the transfer device, is an elevator 20. The elevator may be operated by power drive means (not shown) to convey a load between deck 16 and a suitable storage region located below the deck.

Indicated generally at 22 adjacent the front end of platform 12 is a load station, from which a load may be placed onto the platform (or which may receive a load from the platform). A suitable loading device, such as the one shown in dashed outline at 24, having extensible lift forks 24a may be employed in the load station to transfer loads to, and remove them from, platform 12.

Considering now apparatus 10 in more detail, transfer device 14 is of the type which is described in my priorfiled copending application Ser. No. 557,098, filed June 13, 1966, now Patent No. 3,379,315, for Load-Handling Apparatus. It includes a pair of extensible, elevatable, lift forks 14a, mounted on a turntable 14b which may be swung as a unit about an upright axis. The forks have raised and lowered positions, and while occupying either one of these positions may be extended and retracted. The forks are shiftable between such raised and lowered positions only while extended. Suitable power drive means (not shown herein) is provided for extending, lifting and swinging the forks.

FIG. 1 illustrates various extended and retracted positions of the forks relative to platform 12 and elevator 20. In solid outline at A, the forks occupy a retracted position facing the elevator. In dashed outline at B, the forks occupy an extended position facing the elevator. In position C, the forks have been swung to extend over platform 12. In position D, the forks occupy a retracted position facing the platform.

Suitably mounted on the load transfer device, and indicated generally in block form at 26, 28, are a pair of Patented Jan. 14, 1969 switches. Switch 26 is a normally closed switch which is mounted in such a manner that it opens whenever forks 14a are extended from their retracted position. Switch 28 isa normally closed switch which is mounted in such a manner that it opens upon the forks rotating to a position where they face the support platform (such as positions C, D).

Referring now to FIGS. 1 and 2 together, support platform 12 comprises -a base 13-and a top plate 15 forming the top of the structure. The platform may be secured to the ships deck by means of suitable fasteners, such as those shown at 17, fastening base 13 to the deck.

Mounted on opposite sides of platform 12 are a pair of clamps 29 referred to herein as load-positioning means. The clamps include elongated clamping pads 30 extending along the sides of the platform above plate 15, suitably joined to pairs of pivot arms 32. The pivot arms are mounted on the platform by means of pivot connections, such as those shown at 34, pivoting the arms to base 13 of the platform. Pivot connections 34 enable the clamps to pivot about substantially horizontal axes extending along the sides of the platform. In FIG. 2, the clamps in solid outline are shown in positions where pads 30 are disposed laterally outwardly from the sides of the platform. In dashed outline (FIG. 2) the clamps are shown in upright positions where they have been moved toward each other, and where the pads are located laterally inwardly of the sides of the platform and over plate 15.

Means for shifting the clamps toward and away from one another comprises a pneumatically operated, doubleacting, extensible ram 36 (FIG. 1) suitably mounted on the platform beneath top plate 15. Ram 36 has a rod 36a connected through suitable linkage structure, such as that shown generally at 38, to the clamps. Upon extension of ram 36, the clamps shift toward one another to the positions where thay are illustrated in dashed outline. Upon contraction of the ram, the clamps return to the positions where they are shown in solid outline.

Suitably mounted on the platform beneath plate 15 adjacent rod 36a is a normally open switch 39. This switch is closed by rod 36a upon extension of the ram to place the clamps in their upright position disposed over plate 15.

Also mounted on platform 12 are multiple elongated sensing elements 40, 42, 44, referred to collectively as a sensing means. The sensing elements are approximately midway between opposite sides of the platform. As shown, elements 42, 44 are substantially longer than element 40, and extend almost completely across the width of the platform.

Elements 40, 42, 44 are pivotally mounted on the top plate of the platform, with top faces exposed through suitable openings 46, 48, 50, respectively. Pivoting elements 40, 42, 44 to the top plate are pivot connections 52, 54, 56, respectively, which enable the sensing elements to pivot about horizontal axes extending between the sides of the support platform.

Referring now also to FIG. 3, the sensing elements are illustrated in various raised and lowered positions which they may occupy relative to the top face of platform 12. Elements 40, 42 are shown in solid outline in raised positions where their top faces project slightly above the top face of plate 15 through openings 46, 48, respectively. These two elements are biased to their raised positions by biasing springs shown at 40a, 42a. In dashed outline, elements 40, 42 are shown in their lowered positions. Sensing element 44 is shown in solid outline in its lowered position, and in dashed Outline in its raised position. In its raised position, the top face of element 44 projects through opening 50 well above the top face of plate 15.

Referring to FIG. 2, where sensing element 44 is shown in its raised position, it will be seen that the face is fully exposed to the front end of the platform. This face may bear visual indicating means, and in the embodiment illustrated, the words DO NOT LOAD are suitably marked on the face.

The usual four-way pallet has three parallel base bars extending in one direction thereacross. In FIG. 3, a pallet is shown at 58, with such base bars at 58a, 58b, 58c. The sensing elements are arranged on the platform in such a manner that with a palletized load (that is, a load mounted on such a four-way pallet) properly placed on the platform, only sensing element 40 is engaged by the pallet. This is best illustrated in FIG. 3, where pallet 58 is shown with only element 40 contacted by base bar'58c.

Referring now to FIG. 3, shown generally at 60 is fluid circuit means and at 62 is electrical circuit means as contemplated by the invention. Circuit means 60, 62, together with sensing elements 40, 42, 44, constitute control means herein.

Considering first the fluid circuit means, various valves are employed, and these valves are represented by rectangular outlines, divided by a central line into two squares disposed one above the other. Arrows within the valve outlines illustrate flow paths through the valves. The zig-zag lines outside of and connected with the lower of the two squares represent springs biasing the spools of the valves. These springs urge the spools of the valves upwardly to positions where flow takes place through the valves as shown by the arrows within the bottom squares to which the springs are connected. When the spools are actuated downwardly against the springs, flow takes place through the valves as shown by the arrows within the top squares.

Fluid circuit means 60 comprises a pair of inlet control valves 64, 66 having biasing springs 64a, 66a, respectively, aset of control valves 68, 70, 72, having biasing springs 68a, 70a, 72a, respectively, and a clamping control valve 74 having a biasing spring 74a. The spools of these values are shown in the positions which they normally occupy in the apparatus with the apparatus at rest.

Inlet control valve 64 is a solenoid-operated valve ganged to a solenoid 64b, and the spool of the valve is biased upwardly by spring 64a. Similarly, valve 66 is a solenoid-operated valve ganged to a solenoid 66b, and its valve spool is urged upwardly by spring 66a. Valves 68, 70 have their spools suitably connected to sensing elements 40, 42, and springs 40a, 42a for these elements function to urge the spools of these valves downwardly against the biasing of springs 68a, 70a. Valve 72 has its spool connected to sensing element 44 and its spring 72a urges the spool of the valve upwardly. Valve 74 is a pilotoperated valve, with its spool ganged to fluid motor 74b, and the spool of this valve is urged upwardly by its spring 740.

The fluid circuit means also comprises a fluid-operated ram 82, and previously-mentioned ram 36. Ram 82 is a double-acting ram including a differential piston 82a which is connected by rod 82b and pivot connection 83 to sensing element 44. Upon extension of this ram, sensing element 44 is shifted from its lowered to its raised position, and upon contraction of the ram, the sensing element is returned.

Continuing with a description of the fluid circuit means, at 86 is a supply conduit which is connected to a suitable source of fluid such as air under pressure. Connecting the supply conduit to the inlet control valves are a conduit 88 and a pair of conduits 90, 92. Valves 64, 66 are connected to valve 68 by conduits 94, 96, respectively, and valve 68 is in turn connected to valve 70 by conduit 98.

Valve 70, is connected by means of a conduit to one end of ram 82, and by conduit 102 to valve 72. The other end of ram 82 is connected by a pair of conduits 104, 106 to clamping control valve 74 which is, in turn, connected by a pair of conduits 108, 110 to opposite ends of ram 36. Valve 72 is connected by a pilot line 111 to motor 74b.

Completing the fluid circuit is a conduit 112 which is connected between the junction of conduits 90, 92, and the junction of conduits 104, 106.

Turning now to electrical circuit means 62, it includes a pair of ganged-together single-pole, double-throw switches 120, 122, referred to herein as selecting means, each having a pair of contacts shown for the two switches at 120a, 12012, and 122a, 12217. Also part of the circuit are a main power switch 124, and previously mentioned switches 26, 28, 39.

At 125, 126 is a pair of power supply conductors which are connected to a suitable source of electrical power.

Connected to the electrical circuit means by conductors 127, 128, which are connected to previously mentioned contacts 120a, 120b, respectively, is suitable control equipment indicated generally in block form at 118. Control equipment 118 functions, upon certain conditions existing, which will be explained as the operation of the apparatus is described, to control the operation of the power drive means which produce extension, lifting and swinging of forks 14a. Various other conductors, connecting together the components of circuit means 62, will be described in connection with the discussion of how the apparatus operates.

Considering now how the apparatus described operates, according to the invention the apparatus as earlier indicated has two modes of operation. One of these modes will be referred to herein as an unloading mode, where loads are placed on platform 12 from load station 22 and then unloaded from the platform by device 14, with the latter operating in an unloading cycle. The other is called a loading mode, where loads are transferred by device 14 in a loading cycle to platform 12, and removed from the platform to station 22 by a loading device such as device 24.

Considering first how the apparatus functions during its unloading mode, initially the transfer device occupies the position shown at A in FIG. 1, where forks 14a face the elevator and are retracted and lowered. With the device in this position, switches 26, 28 are closed. Clamps 29 occupy a spread-apart position due to pressurized air being supplied through conduits 86, 90, 112, 106, valve 74, and conduit 110 to ram 36 causing the ram to contract. With ram 36 contracted, switch 39 is open. Ram 82 for sensing element 44 is also initially contracted (and element 44 lowered), due to pressurized air being supplied to the ram through conduits 86, 90, 112, 104.

To select the unloading mode of operation, switches 120, 122 are switched to positions where they meet contacts 120b, 122b, respectively, and to place the apparatus in a condition where it is ready to operate, main power switch 124 is closed.

Upon closing of switch 124, a circuit is completed which supplies power to solenoid 64b comprising switch 124, a conductor 130, limit switches 26, 28 (which are connected in parallel), switch 122, a conductor 134, solenoid 64b, a conductor 136, and a conductor 138 which is connected to power supply conductor 125. This causes solenoid 64b to energize with downward movement of the valve spool for valve 64.

With this adjustment, conduit 88 which is connected to supply conduit 86 is connected through the valve to conduit 94. Conduit 94, however, is closed off by valve 68, and nothing further occurs in the apparatus until a load is placed on platform 12 from load station 22.

Let it be assumed that a load mounted on a pallet, such as pallet 58, is brought to the load station by loading device 24, and is properly placed on the support platform. It will be recalled that pallet 58 is shown in such a position on the platform (FIG. 3). With the load thus placed on the platform, an end support of the pallet engages sensing element 40, causing depressing of the element to its lowered position.

Upon lowering of sensing element 40, the spool of valve 68 is shifted upwardly. With such an adjustment, fluid flows from conduit 94 through the valve to conduit 98, thence through valve 70, to conduit 100.

Air under pressure is thus supplied to both ends of ram 82, and under such circumstances, differential piston 82a shifts upwardly causing movement of sensing element 44 from its lowered toward its raised position.

If the lift forks of loading device 24 are not yet retracted from beneath the pallet on the platform, sensing element 44 will engage such forks, and be prevented from fully reaching its raised position. Until sensing element 44 reaches its raised position, and hence, until forks 24a which placed the load on the platform are retracted from beneath the pallet, nothing further occurs in the apparatus. The reason for preventing any further operation of the apparatus at this point is to prevent any chance of forks 14a of transfer device 14 being extended beneath the pallet while another set of forks is still there.

As soon as forks 24a are retracted from beneath the pallet, sensing element 44 moves up to its fully raised position. With the load thus properly placed on the platform relative to the platforms front and rear ends, and forks 24a fully retracted from beneath the load, a predetermined load condition exists for the loading mode of operation. In this predetermined load condition, sensing element 40 occupies its lowered position, and elements 42, 44 occupy their raised positions.

With raising of element 44, the valve spool of valve 72 moves downwardly connecting conduit 102 to pilot line 111. The valve spool of valve 74 as a consequence is shifted downwardly. Conduits 112, 108 are connected through valve 74. Ram 36 extends, causing clamps 29 to move toward each other and against opposite sides of the load. Such movement of the clamps produces centering of the load relative to the sides of the platform.

Extension of ram 36 also causes switch 39 to close. When this switch closes, power is supplied to control equipment 118 through a circuit including supply conductor 126, main power switch 124, conductor 130', a conductor 142, switch 39, a conductor 144, switch 120, conductor 128, control equipment 118, and a conductor 148 which connects control equipment 118 to supply conductor 125.

Upon power being supplied to the control equipment, an appropriate holding circuit is completed (within equipment 118, and not shown), whereby power is supplied to equipment 118 independently of switch 39, this circuit including a conductor 149 which connects the equipment to conductor 130. Control equipment 118 then controls the operation of transfer device 14. Such equipment is of a nature so as to produce swinging of lift fork 14a from position A to position D, and then extension of the forks beneath the load on platform 12, to position C.

With the forks in position C, switches 26, 28 are both open (switch 28 being in such a position so as to be opened upon the forks swinging to position D, and switch 26 being in such a position so as to be opened upon the forks extending out toward position C). Hence, the circuit previously described supplying power to solenoid 64b is broken, whereupon the solenoid is deenergized. This causes valve 64 to return to its raised position with conduit 94 exhausting to the atmosphere. When this occurs, ram 82 contracts, by reason of air exhausting from the ram through conduit 100, valve 70, conduit 98, valve 68, to conduit 94. Motor 741; is deactuated, with air exhausting from the motor from line 111.

Upon contraction of ram 82, sensing element 44 returns to its lowered position, with raising of the spool of valve 72. Deactuation of motor 74b permits the valve spool of valve 74 to raise with conduit again being connected to the source of pressurized air through valve 74 and conduits 106, 112, and 90. Additionally, conduit 108 is again connected through the valve to atmosphere. This causes ram 36 to contract, whereupon clamps 2.9 are released from the sides of the load, and limit switch 39 opens.

It should be noted that during the period of time when forks 14a face platform 12 and are extended, switches 26,

28 each remain open and prevent any circuit from being completed which would again supply power to solenoid 64b. This is important, since if solenoid 64b were energized under such circumstances, the clamps would again be brought against the sides of the load and prevent it from being lifted easily from the support platform.

Control equipment 118 is so designed that with forks 14a occupying position C, and with the clamps released from the sides of the load, the equipment 118 causes elevation of the forks to pick up the load, and then fork retraction while holding the load. The forks are then swung back as controlled by the equipment to a position where they face elevator 20. Control equipment 118 functions further, upon elevator 20 being raised to the level of deck 16 and being free of any load, to cause the forks to be extended out over the elevator to position B, and lowered to set the load down on the elevator. The forks are then retracted while under the control of equipment 118so that they again occupy position A. The elevator may then be lowered below deck 16, unloaded, and raised again. Upon the forks being retracted to position A after depositing the load on the elevator, control equipment 118 breaks the hOlding circuit previously described supplying it with power. The apparatus is then ready to receive and handle another load.

Considering now what happens when a properly palletized load is placed too far toward rear end 12b of platform 12, a base bar of the pallet will still engage and lower sensing element 40, as before. Additionally, however, the pallets center base bar (bar 58b) will engage and lower sensing element 42.

Upon lowering of element 40, valve 68 is actuated to connect conduits 94, 98 whereupon pressurized fiuid is supplied to conduit 98. Upon lowering of element 42, the valve spool of valve 70 rises, whereupon air flow through the valve between conduits 98, 100 is blocked, and conduit 100 is connected through the valve to the atmosphere.

' With conduit 100 connected to the atosphere, ram 82 remains contracted, sensing element 44 remains lowered, and valve 72 remains in the position in which it is shown, where air flow through the valve betwen conduits 102, 111 is blocked and conduit 111 is connected through the valve to atmosphere. With conduit 111 connected to the atmosphere, no extension of motor 74b occurs which would actuate valve 74. Hence, ram 36 remains contracted, and switch 39 remains open. So long as switch 39 remains open, no power can be supplied to control equipment 118 which would initiate operation of transfer device 14.

The reason why it is important in this case to prevent operation of the transfer device is that a load so placed on the platform, if picked up by forks 14a, would be positioned too far along the forks in a "direction extending inwardly from their outer ends, and the forks would not place such a load properly on the elevator.

Considering now the situation when a properly palletized load is placed too far to the front of platform 12, when this occurs, none of the pallets supports engage any of the sensing elements. Hence, valves 68, 70, 72, 74 remain in the positions in which they are shown, and

rams 36, 82, and motor 74b remain contracted. With ram 36 contracted, switch 39 remains open, and no power is supplied to control equipment 118 to initiate operation of the transfer device.

The reason why it is important to prevent operation of the transfer device when a load is placed too far to the front of the platform is that such a load, if picked up by forks 14a, would be positioned too far toward the outer ends of the forks where it might not be fully supported. Additionally, if the load happened to extend beyond the ends of the forks, upon swinging of the forks toward the elevator, the load might accidentally strike an obstruction.

Explaining what happens in the event a nonpalletizedload is placed on platform 12, sucha load would engage sensing element 42, shifting the element to its lowered position. When this occurs, valve 70 is actuated to prevent any air from flowing between conduits 98, 100, and the same operation results as previously described when element 42 is depressed. It will be apparent that the reason for preventing the transfer device from operating when a nonpalletized load is placed on the platform is to prevent the lift forks from ramming into the load upon being ductor 150, solenoid 66b, a conductor 152, conductor 138, and supply conductor 125. Upon energizing of solenoid 66b, the valve spool of valve 66 is shifted downwardly, whereupon fluid under pressure flows through the valve to conduit 96.

Pressurized fluid or air is then supplied to the lower end of ram 82. It will be recalled that as an initial condition air, having the same pressure as air in conduit 100, is also being supplied to ram 82 through conduits 112, 104.

With air supplied to both ends of ram 82, differential piston 82a shifts to cause extension of rod 82b, whereupon sensing element 44 is shifted to its raised position. With shifting of sensing element 44 to its raised position the spool of valve 72 lowers, with connecting of conduits 102, 111, whereupon pressurized air is supplied pilot line 111 and motor 74b. Valve 74 is actuated by lowering of its valve spool to connect conduits 106, 108 and to connect conduit 110 to the atmosphere. Pressurized air is thus supplied from supply conduit 86 to ram 36 causing the ram to extend. Extension of ram 36 causes closing of switch 39.

With switch 39 closed, the apparatus is now in readiness to carry out loading or to prevent such from occurring, depending upon the conditions existing on the top of load platform 12. With the platform free of any load all three sensing elements occupy their raised positions, which is a predetermined load condition permitting the loading mode of operation to take place. It should be particularly noted that with this predetermined load condition sensing element 44 has its top face facing load station 22. This serves to give a visual indication as seen in FIG. 2 to anyone in the load station that the apparatus is prepared to operate in its unloading mode of operation, and it is not intended to receive loads from station 22 as during an unloading type operation. Words such as DO NOT LOAD marked on the face of the element serve as an additional precaution to anyone in station 22.

In the event that a load is inadvertently placed on the platform from the load station, the apparatus functions to prevent the possibility of transfer device 14 operating while such a load remains on the platform. A load so placed on the platform would engage at least one of the three sensing elements, urging the element to its lowered position. It will be apparent that if any one of the sensing elements is lowered, the valve connected to the element is actuated in such a manner as to block off the supply of pressurized air to motor 74b. Additionally, actuation of any one of valves 68, 70, 72 results in conduit 111 being connected to atmosphere.

When this occurs, motor 74b is deactuated, and biasing spring 74a of valve 74 raises the valve spool. This results in contraction of ram 36 and reopening of switches 39. With switch 39 open, no operation of transfer device 14 is possible. This situation will remain until the load is removed from platform 12, whereupon all sensing elements again occupy their raised positions.

Continuing with a description of the loading mode of operation, during this mode elevator 20 is used to convey loads to the level of deck 16 from regions below the deck where the loads are stored. It is assumed that all such loads carried by the elevator were initially loaded onto the ship by apparatus 10, and hence, are properly palletized. It is assumed also that such loads are positioned on the elevator when it arrives at the level of deck 16, whereby the lift forks of transfer device 14 may readily be extended beneath the load to pick it up off the platform.

With platform 12 clear of any load, and upon elevator 20 holding a load and being positioned at the level of deck 16, control equipment 118 is designated so that a holding circuit therein is completed whereby power is supplied to the equipment independently of switch 39. Upon completion of this holding circuit, the control equipment 118 initiates operation of the load transfer device with forks 14a first being extended beneath the load on the elevator, then elevated to pick up the load, and then retracted. Under the control of equipment 118, the forks are then swung to where they face the platform, and subsequently extended out over the platform. With such swinging and extension of the forks, switches 26, 28 are both opened, and the circuit previously described supplying power to solenoid 66b is broken.

With solenoid 66b de-energized, the valve spool of valve 66 rises whereby fiow between conduits 92, 96 is blocked off, and conduit 96 is connected to the atmosphere. Thus, the supply of pressurized air to motor 74b, and to the bottom end of ram 82 is cut off, resulting in contraction of the latter and deactuation of motor 74b.

Ram 82 contracts due to pressurized air still being supplied to its upper end connected to conduit 104. Such contraction results in lowering of sensing element 44 and raising of the spool of valve 72 with line 111 then connecting with the atmosphere through valve 72. With line 111 connected to the atmosphere, the valve spool of valve 74 rises.

The results in ram 36 being contracted, whereupon the clamps move away from one another, and return to the positions in which they are shown in solid outline. Such movement of the clamps is important in order that the load held by transfer device 14 may readily be placed on the platform without any chance of striking one of the clamps.

Equipment 118 is so designed as to cause forks 14a then to lower to place the load upon the platform, then to retract, and then to swing back to position A. With the device again occupying position A, the holding circuit which is part of equipment 118 is broken.

Upon such retraction and swinging of the forks, limit switches 26, 28 again close, whereupon power is again supplied to energize solenoid 6612. Upon energizing of the solenoid, the valve spool of valve 66 returns to its lowered position.

The load on the platform may be removed by loading device 24 located in the load station, and the load carried away. With removal of the load from platform 12, all of the sensing elements again occupy their raised positions, whereupon motor 74b is again supplied with pressurized air, and actuated to lower the spool of valve 74. Upon such lowering of the spool, pressurized air is again supplied to ram 36 causing extension of the ram and closing of switch 39. The apparatus is then ready to handle another load brought up to the deck by the elevator.

Thus the invention provides apparatus for handling palletized loads which has a number of advantages. In one mode of operation the apparatus is adapted to receive loads on its support platform, and in this mode, the apparatus requires that certain load conditions exist on the platform before any steps of automatic handling are undertaken. Specifically, it on a pallet, that such a load be properly positioned on the platform, and that any forks which are used to place the load on the platform be fully withdrawn from beneath the load. Novel sensing elements mounted on the platform function to determine that these conditions are met, and prevent any automatic operation of the apparatus when the conditions are not met.

In another mode of operation, the transfer device of the apparatus is adapted to place loads on the support platform where they may readily be removed from the apparatus. Also, in this mode of operation as in the other, the apparatus requires that a certain load condition exist on the platform prior to the transfer device placing any load there. In this instance, the sensing elements on the platform function to indicate the presence of any load at all being on the platform. The transfer device is permitted to place a load on the platform only when the sensing elements detect that the platform is then free of any load.

During this mode of operation, visual indicating means is provided which warns against the placing of loads on the platform by means outside the apparatus.

While an embodiment of the invention has been shown and described herein, it is appreciated that variations and modifications may be made without departing from the spirit of the invention. Accordingly, it is intended to cover all such variations and modifications which would be ap parent to one skilled in the art and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. Apparatus for automatically handling palletized loads comprising a support platform for receiving and holding a load,

a load transfer device located adjacent said support platform operable to transfer a load to and from said platform,

multiple sensing elements mounted on said support platform, each element having a raised and a lowered position which it may occupy relative to the top face of said platform, said elements indicating the load condition existing on said platform at a given time according to the positions which they occupy, and

means operatively interconnecting said sensing elements and said load transfer device operable, upon said elements indicating a predetermined load condition existing on said support platform, to effect operation of said transfer device.

2. The apparatus of claim 1 which has one mode of operation where said transfer device is operable, upon one predetermined load condition existing on said platform, to remove a load from said support platform, and another mode of operation where said device is operable, upon another predetermined load condition which is different from said one predetermined load condition existing on said platform, to transfer a load to said platform, and which further comprises means for selecting one of said modes of operation for said apparatus.

3. The apparatus of claim 2, wherein said support platform is positioned closely adjacent a load station, during said one mode of operation, a load is taken from said station and placed on said platform, during said other mode of operation, a load is removed from said platform and placed in said load station, and wherein, with said selecting means selecting said other mode of operation for said apparatus, one of said sensing elements includes visual indicating means facing the load station warning against the taking of a load from the station and placing it on the platform 4. The apparatus of claim 2, wherin said multiple sensing elements include first, second and third elements, and with said selecting means selecting said one mode of operation for said apparatus, said elements indicate said one predetermined load condition existing on said platform upon said first element occupying its said requires that a load be mounted lowered position, and said second and third elements occupying their said raised positions.

5. The apparatus of claim 4, wherein said support platform is positioned closely adjacent a load station from which a loading device in the station may be extended over said platform to place a load thereon, and said third sensing element, during said one mode of operation, is engageable with such a loading device with the latter extended over the platform, and while so engaged, is prevented from occupying its said raised position.

6. The apparatus of claim 2, wherein said multiple sensing elements include first, second and third elements, and with said selecting means selecting said other mode of operation for said elements, said elements indicate said other predetermined load condition existing on said platform upon each of said elements occupying its said raised position.

7. The apparatus of claim 2, wherein the means interconnecting said sensing elements and load transfer device comprises fluid circuit means operatively connected to said sensing elements, and said elements function to control the flow of fluid in said fluid circuit means according to the positions which they occupy.

8. The apparatus of claim 7, wherein said fluid circuit means includes a ram which, with said apparatus operating in its said one mode, is actuated upon said sensing elements indicating said one predetermined load condition existing on said platform, and which further comprises load-positioning means mounted on said platform operatively connected to said ram operable, upon actuation of the ram, to adjust the lateral position of a load resting on said platform.

9. Material handling apparatus comprising a load support platform,

a power-operated load transfer device located adjacent said platform constructed to permit transfer of a load between locations on and to one side of the platform, and

selectable control means controlling operation of said transfer device having one selected condition where the transfer device operates in a loading cycle to transfer a load onto the platform, and another selected condition where the transfer device operates in an unloading cycle to transfer a load off of the platform,

said control means including sensing means adjacent said platform for sensing the load condition existing thereon and operable with the control means in its said one condition to actuate the transfer device in a loading cycle in the absence of a load on the platform, said sensing means being further operable with the control means in its said other condition to actuate the transfer device in an unloading cycle with a load present on the platform.

10. The apparatus of claim 9, wherein said sensing means comprises sensing elements which occupy one state with a palletized load supported in a properly centered position on said platform, and another state with such a load supported to one side of such position, said sensing elements preventing actuation of said transfer device when occupying their said other state with said control means in its said other selected condition.

11. The apparatus of claim 10, wherein said sensing elements occupy still another state with a nonpalletized load supported on said platform, said elements preventing actuation of the transfer device when occupying their said last-mentioned state with the control means in either of its said selected conditions.

References Cited UNITED STATES PATENTS 3,232,455 2/1966 Fountain of al. 2l4-l6.4 3,272,347 9/1966 Lemelson 214-164 ROBERT G. SHERIDAN, Primary Examiner.

US. Cl. X.R. 

